The 5 Cars That Wheeled Across the Moon

All five rovers that the Soviet Union and the U.S. left on the moon in the 1970s have been found by a NASA orbiterand three are still used today for gathering data.

All five rovers that the Soviet Union and the U.S. left on the moon in the 1970s have been found by a NASA orbiter—and three are still used today for gathering data.

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NASA

The 5 Cars That Wheeled Across the Moon

NASA's Lunar Reconnaissance Orbiter (LRO) headed to the moon in June 2009 with a camera system and a suite of other instruments it would use to measure the surface. The LRO's high-resolution images would build maps far more detailed than those used by the Apollo missions. In fact, it even spotted the relics of those missions: rovers left by the Apollo and Soviet Luna missions in the 1960s and 1970s.

There are five cars on the moon, still sitting there 40 years after their heyday. The Soviets were the first to do it. In 1970, the Luna 17 spacecraft landed a remote-controlled, eight-wheeled, seven-foot-long car on the moon. Later, the U.S. one-upped the USSR by landing three manned vehicles on the surface. In 1971 and 1972 Apollo 15, 16, and 17 carried 10-foot-long LRVs (lunar roving vehicles). The final rover to land on the moon was from the Soviet Luna 21 mission in 1973.

On the earlier Apollo missions, astronauts on the moon had to pull wheeled carts full of equipment to drill and sample soil and set up cameras and antennae. The NASA rovers used mounts for equipment, and allowed the astronauts to venture farther away from their landing-module base camps. These rigs were vital to both the Soviet and U.S. space programs. Here's a deeper look at the five rovers that first landed on the surface of the moon and their missions.

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NASA

Lunakhod 1

In November 1970 the Soviet spacecraft Luna 17 touched down on the moon and deployed a ramp; then the seven-foot-long, five-foot-tall Lunakhod 1 remote-controlled rover drove onto the surface. Lunakhod 1 used eight electrically powered wheels and carried equipment such as cosmic-ray detectors and spectrometers. It hauled along four video cameras and antennae that sprouted from the bathtub-like body of the rover to transmit video back to Earth. The antennae also received commands from the scientists on Earth who operated remote arms to collect samples, examine the moon's surface, and send photos back.

Solar cells powered all the equipment; they received a long charge during the lunar daytime (equal to about 13 earth days). The rover then hunkered down for the very long, very cold night. A small nuclear heater kept Lunakhod 1 from freezing every night, when temperatures would drop to minus 240 degrees Fahrenheit.

The Soviet scientists planned on Lunakhod 1 operating for about three spells of lunar daytime (about 40 earth days of operational time, not counting the lunar nighttime when the rover slept). But the remarkable unit lasted almost four times as long, until September 1971, and covered about 10 kilometers (6.2 miles) during that time. When it finally lost touch with its earthbound operators, Lunakhod 1 had performed hundreds of geological tests and sent back thousands of photos. It had wandered into an area invisible to telescopes on Earth. In fact, its exact final location was a mystery until March 2009, when NASA's LRO cameras spotted it.

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NASA

Apollo 15 Lunar Roving Vehicle 1

The first Boeing-built four-wheel rover, deployed on Apollo 15 in July 1971, was used for three separate lunar excursions totaling 16.5 miles. Average speed: about 6 mph. After astronauts David Scott and James Irwin landed on the moon, they spent 45 minutes unstowing the LRV and unfolding its three-section aluminum-ladder frame. The LRV was powered by four 1/4-hp electric motors (one in each wheel), and the astronauts steered it via an electric rack on each independently sprung axle.

On the astronauts' first lunar (off)road trip, the front wheels would not steer but the rear wheels would. Even with this slight mechanical defect, the pair set out for a 3-mile jaunt. Scott reported the ride on the rocky, cratered surface to be quite bouncy. For safety on further trips, the astronauts limited their distance from the lunar module home base to about 6 miles—that was estimated to be the longest distance they could safely walk back without running out of air.

On the astronauts' second drive, Scott spun the LRV on the dusty surface. As with Lunakhod 1, the LRV's wheels were made of wire mesh, so unintentionally fishtailing the rig must have been easy.

On the third rover trip, Scott parked the two-seat rover on a slope at the base of the Hadley Delta mountain. When he stepped out of the rover, it started to slide downhill. Because of the low gravity, Scott was able to grab it and stop the slide. This trip was the longest single traverse, at about 7.5 miles.

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NASA

Apollo 16 Lunar Roving Vehicle 2

The Apollo 15 rover was a solid machine, so the only functional upgrade NASA made to the second LRV was easier-to-use seatbelts. In April 1972 Apollo 16 landed on the moon and astronauts John Young and Charles Duke drove their rover on three separate journeys. Like the previous mission, the distances and speeds were about the same, totaling 16 miles at an average of about 5 mph.

Young and Duke had been involved in the development of the LRVs, and they came up with the idea of using a simple T-handle to control steering, acceleration, and braking. A switch on the T-handle put the rover in reverse. On their first trip, the duo ventured about 3 miles away from the lunar module, which had landed in the Descartes Highlands region of the moon, an area known for magnetic anomalies as well as a combination of old and new craters. That first drive in the rover was a loop to Flag Crater and then Spook Crater, where Young and Duke picked up 44 pounds of moon rocks.

The second trip, on the second earth day of the mission, was to Cinco Craters and Stone Mountain. The last trip, to North Ray Crater, was where the famous photos of House Rock ("Looka the size of that rock!" Duke said at the time) and Shadow Rock were taken. During the three trips, the crew picked up more than 200 pounds of rocks.

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NASA

Apollo 17 Lunar Roving Vehicle 3

In December 1972 Apollo 17 astronauts Harrison Schmitt and Gene Cernan discovered a new difficulty of driving a rover on the moon's surface. While Cernan was walking by the rover, the hammer pocket of his suit caught one of the front fenders and tore it off. And without fenders to cover the wheels, the rover kicked up so much dust that they couldn't see. The fix, of course, was duct tape, but only after the astronauts took the broken part into the lunar module—too much dust outside kept the duct tape from sticking.

Schmitt and Cernan also claimed the fastest speed and the greatest distance in their three rover drives. Coming down a steep hill, their vehicle reportedly hit about 10 mph. The rovers were equipped with a gyroscopic readout and an odometer, both of which would come in handy. The longest journey the pair drove the LRV was 12 miles, and their total distance in the rover during the mission was 21.5 miles. The adventuresome pair drove the rover 4.5 miles from the safety of the lunar module.

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NASA

Lunakhod 2

In January 1973 the last rover was sent to the moon's surface—the remote-controlled Lunakhod 2. Like the Soviets' previous vehicle, Lunakhod 2 was an eight-wheeler packed with cameras and sensors, and it featured an internal nuclear heater to survive freezing lunar nights. Because there is insufficient atmosphere on the moon to trap sunlight, bottoms of dark craters near the lunar poles that never receive sunlight are as close to absolute zero as any place in space.

Yet even in these conditions, Lunakhod 2 ran for four months. At that point it was speculated that Lunakhod 2 overheated because of moon dust clogging some of its mechanics.

Still, the whereabouts of Lunakhod 2 have been known for decades; its reflector antenna has been visible to astronomers and other scientists on Earth. This antenna, when a laser is reflected off it, lets scientists monitor size fluctuations. (The Apollo missions also left reflectors on the moon that allow scientists to track its exact distance from Earth, speed, and orbit, but researchers needed another reflector to capture the tiny variations in the moon's size. Understanding that could help lead to a better understanding of exactly what the moon is made of.)

The Lunakhod 2 traveled about 20 miles during its road trips on the moon, sending back climate data, video, and photographs. It roamed the 30-mile wide Le Monnier crater that edges up to the Sea of Serenity dry lakebed—an area adjacent to the famous Sea of Tranquility, where Armstrong and Aldrin walked on the moon's surface. The final observation of Lunakhod 2 was a view of the Fossa Recta trench inside the Sea of Serenity, before its instruments went silent.

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